Oil and natural gas wells often utilize borehole components or tools that, due to their function, are only required to have limited service lives that are considerably less than the service life of the well. After a component or tool service function is complete, the downhole component or tool must be removed or disposed of in order to recover the original size of the fluid pathway for use, including hydrocarbon production, CO2 sequestration, etc. Disposal of components or tools has conventionally been done by milling or drilling the component or tool out of the borehole, which is generally a time consuming and expensive operation.
In order to eliminate the need for the milling or drilling operation, the removal of components or tools by dissolution of degradable material using various borehole fluids has been proposed. The degradable materials that have been proposed include certain degradable metal alloys formed from reactive metals, such as aluminum, together with other alloy constituents, such as gallium, indium, bismuth, tin, and mixtures and combinations thereof. These materials may be formed by melting powders of the constituents and then solidifying the melt to form the alloy. They may also be formed using powder metallurgy by pressing, compacting, sintering and the like a powder mixture of a reactive metal and other alloy constituent in the various amounts. To degrade the metal alloys, and thus effectively remove the component or tool from the borehole, strong mineral acids or brine has been used. However, the corrosion rate of mineral acids may be too fast while the corrosion rate brine may be too slow under downhole conditions.
Advances that avoid the above noted problems would be well received in the art.